The explicit top-down approach and the correlated implicit bottom-up approach to learning relate to the concepts of explicit and implicit knowledge and how best to acquire the needed one and the needed cognitive skills. Top-down knowledge is that which goes from the general explicit concept to specific implicit application through deductive reasoning. Bottom-up knowledge is that which goes from observed implicit specifics to general explicit conclusions through inductive reasoning. The aim of each approach is to arrive at both explicit knowledge and implicit knowledge but by going from two different directions, though studies show this aim is not fully realized especially pertaining to the bottom-up approach.
In top-down, the student goes from receiving knowledge from an instructor to acquiring related implicit knowledge through application and expansion of the explicit knowledge. This uses deductive reasoning going from the general rule or theory to specific applications or observations. In bottom-up, the student starts with a topic or a question, performs self-directed research and study and ultimately arrives at explicit knowledge. This uses inductive reasoning going from the specific observations to the general rule.
Sun and Zhang, in "Top-down versus bottom-up learning in cognitive skill acquisition," indicate that top-down may be the better approach for "highlevel, highly structured, cognitive skill" tasks because they require "high-level, explicit thinking ... [with] explicitly encouraged goal recursion." Conversely, a Sun et al. 2001 study showed "the necessity of bottom-up learning in low-level skill domains." Sun and Zhang conclude that while top-down is vital for highlevel cognitive skill acquisition, top-down and bottom-up lowlevel skill acquisition interact and work together: "human skill acquisition processes often involve both implicit and explicit processes [of human skill acquisition] and thus involve their interaction (Sun et al., 1998, 2001, 2003)."